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How Minerals Form

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Vocabulary

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vein-a slab of mineral where it is different from the other rocks
solution- a mixture where one substance dissolves in another

Outline

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Processes That Form Minerals

• minerals that have been forming in Earth's Crust for billions of years
  • two ways crystals form
    • through crystallization of melted materials
    • through crystallization of materials dissolved in water

Materials From Magma

• minerals form as magma cools inside crust or lava on the surface
  • when these liquids cool, they form crystals
    • crystal size depends upon several key factors
      • the rate of cooling
      • how much gas in the liquid
      • the chemical composition of the magma
• when magma stays below surface, it cools for thousands of years
  • slow cooling forms large crystals
    • Magma closer to the surface,cools rapidly
    • quick cooling creates smaller crystals

Minerals From Hot Water Solutions

• the elements that form a mineral can also dissolve in hot water
  • magma heats the water under Earth's surface to a high temperature
  • dissolved minerals form solutions
  • When it begins to cool,the compounds and elements leave the solution
  • Soon, they crystallize as minerals
• metals that form underground from hot water solutions often form veins
  • solutions of hot water and metal often seep through cracks underground
    • the metal then crystallize into veins
• minerals can form along the mid-ocean ridge
  • first the ocean water sinks through the ocean crust
  • the water comes in contact with the magma
    • the water heats to a very high temperature
  • the heated water dissolves minerals and rushes upward
  • this solution sprays out of chimneys(vents in the oceanic crust)
  • when the solution hits the sea the minerals crystallize and sink to the ocean floor

Minerals Formed by Evaporation

• minerals can also form by evaporation
  • if you mix salt with water to make a solution,the water will evaporate and you will see salt crystals at the bottom of the cup
  • the mineral, halite forms from evaporation
• Some minerals form from evaporation of seawater
  • these minerals are gypsum, calcite crystals, and minerals containing pottasium

Where Minerals are Found

• the crust is mostly made up of rock forming minerals
  • many valuble minerals are found near volcanic activity and mountain building
    • California's gold was found along the Sierra Nevada mountains

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